Simple Excel question

The starting point is that, when Excel shows the result to be 14.21, that is the correct result to the problem as posed.  It is far more likely that you have formulated the wrong problem than it is that the Excel calculation engine has given the wrong answer. 

As HansVogelaar  suggests, the  value contained in cell A1 will be closer to 3.77 than it is to 4.  The fact that you see 4 in cell A1 is due to the formatting.  It affects the presentation but not the value of the underlying number.